Index: test/CodeGen/attr-optnone.c
===================================================================
--- test/CodeGen/attr-optnone.c	(revision 223920)
+++ test/CodeGen/attr-optnone.c	(working copy)
@@ -9,7 +9,7 @@
 int test2() { return 0; }
 // OPTSIZE: @test2{{.*}}[[ATTR2:#[0-9]+]]
 
-__attribute__((optnone)) __attribute__((minsize))
+__attribute__((optnone))
 int test3() { return 0; }
 // PRESENT-DAG: @test3{{.*}}[[ATTR3:#[0-9]+]]
 
Index: test/SemaCXX/attr-optnone.cpp
===================================================================
--- test/SemaCXX/attr-optnone.cpp	(revision 223920)
+++ test/SemaCXX/attr-optnone.cpp	(working copy)
@@ -6,6 +6,9 @@
 int baz() __attribute__((always_inline)) __attribute__((optnone)); // expected-error{{'always_inline' and 'optnone' attributes are not compatible}}
 int quz() __attribute__((optnone)) __attribute__((always_inline)); // expected-error{{'optnone' and 'always_inline' attributes are not compatible}}
 
+int bay() __attribute__((minsize)) __attribute__((optnone)); // expected-error{{'minsize' and 'optnone' attributes are not compatible}}
+int quy() __attribute__((optnone)) __attribute__((minsize)); // expected-error{{'optnone' and 'minsize' attributes are not compatible}}
+
 __forceinline __attribute__((optnone)) int bax(); // expected-error{{'__forceinline' and 'optnone' attributes are not compatible}}
 __attribute__((optnone)) __forceinline int qux(); // expected-error{{'optnone' and '__forceinline' attributes are not compatible}}
 
Index: test/SemaCXX/pragma-optimize.cpp
===================================================================
--- test/SemaCXX/pragma-optimize.cpp	(revision 223920)
+++ test/SemaCXX/pragma-optimize.cpp	(working copy)
@@ -55,6 +55,13 @@
 }
 // CHECK-DAG: @_Z3bazi{{.*}} [[ATTRBAZ:#[0-9]+]]
 
+// This function definition will not be decorated with `optnone` because the
+// attribute would conflict with `minsize`.
+int __attribute__((minsize)) bax(int z) {
+    return foo(z, 2);
+}
+// CHECK-DAG: @_Z3baxi{{.*}} [[ATTRBAX:#[0-9]+]]
+
 #pragma clang optimize on
 
 // The function "int wombat(int param)" created by the macro is not
@@ -144,6 +151,7 @@
 // Check that the other functions do NOT have optnone.
 // CHECK-DAG-NOT: attributes [[ATTRFOO]] = { {{.*}}optnone{{.*}} }
 // CHECK-DAG-NOT: attributes [[ATTRBAZ]] = { {{.*}}optnone{{.*}} }
+// CHECK-DAG-NOT: attributes [[ATTRBAX]] = { {{.*}}optnone{{.*}} }
 // CHECK-DAG-NOT: attributes [[ATTRWOMBAT]] = { {{.*}}optnone{{.*}} }
 // CHECK-DAG-NOT: attributes [[ATTRCONTAINER]] = { {{.*}}optnone{{.*}} }
 // CHECK-DAG-NOT: attributes [[ATTRTWICE]] = { {{.*}}optnone{{.*}} }
Index: lib/Sema/SemaDeclAttr.cpp
===================================================================
--- lib/Sema/SemaDeclAttr.cpp	(revision 223920)
+++ lib/Sema/SemaDeclAttr.cpp	(working copy)
@@ -3146,10 +3146,22 @@
                               Attr.getAttributeSpellingListIndex()));
 }
 
+static void handleMinSizeAttr(Sema &S, Decl *D,
+                              const AttributeList &Attr) {
+  if (checkAttrMutualExclusion<OptimizeNoneAttr>(S, D, Attr))
+    return;
+
+  D->addAttr(::new (S.Context)
+             MinSizeAttr(Attr.getRange(), S.Context,
+                         Attr.getAttributeSpellingListIndex()));
+}
+
 static void handleOptimizeNoneAttr(Sema &S, Decl *D,
                                    const AttributeList &Attr) {
   if (checkAttrMutualExclusion<AlwaysInlineAttr>(S, D, Attr))
     return;
+  if (checkAttrMutualExclusion<MinSizeAttr>(S, D, Attr))
+    return;
 
   D->addAttr(::new (S.Context)
              OptimizeNoneAttr(Attr.getRange(), S.Context,
@@ -4340,7 +4352,7 @@
     handleExtVectorTypeAttr(S, scope, D, Attr);
     break;
   case AttributeList::AT_MinSize:
-    handleSimpleAttribute<MinSizeAttr>(S, D, Attr);
+    handleMinSizeAttr(S, D, Attr);
     break;
   case AttributeList::AT_OptimizeNone:
     handleOptimizeNoneAttr(S, D, Attr);